Slate brick



Patented July 24, T923.

EMIL P. ENGELIIBRECHT, OF CHICAGO, ILLINOIS.

SLATE harem We Drawin.

To all whom it may concern Be it known that I, EMIL P. ENGELBRECHT, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Slate Bricks, of which the following is a specification.

This invention relates to bricks, tiles, and the like, and consists in a novel process for manufacturing bricks, tiles, and other articles which are required to be of the general nature of bricks. The invention consists also in the novel product produced by the carrying out of my process. For convenience I shall refer herein to the products merely as bricks, but it is to be understood that in general the statements refer to tiles and other similar articles as well.

One of the purposes of my process is to produce bricks which will withstand very intense heat continuously for a long time, and hence are ordinarily called fire-bricks. Another purpose is to producebricks of the nature that will be fully as effective as ordinary fire-bricks, as to durability, looks, and

the like, but that will be less expensive to manufacture.

The process which I have invented for manufacturing these bricks consists in using as the principal material therefor, what is ordinarily ca led red dog. This is a substance which is formed from coal-mine slate which is a grayish slaty substance which is formed in the shape of veins in coal beds, and is separated from the coal as it is mined, and ordinarily thrown out as waste. This slate is thrown out by the miners into enormous piles of thousands of tons, and spontaneous combustion arises therein and the combustible substances contained in the slate, such as sulphur, and the like, are

burned out. This burned substance is called red dog.

My invention consistsin taking this burned slate and crushing it and then grinding it into fine particles, somewhat smaller than ordinary grains of sand. I refer, to grind it up until the larger partic es are no more than about one-sixteenth of an inch thick. I then add a; small proportion of unslacked lime,-.in the neighborhood of from three to; five per cent; the greater the percentage of lime, the stronger the brick. For the best quality of fire-brick about five per cent-of lune is used.

This ground slate and lime is then mixed Application filed May 25, 1 921. Serial No. 472,573.

thoroughly and is passed into a grinding mill, and the mixture is thoroughly ground together With a suitable amount of water. Just enough water is used to properly slack the lime without any surplus water, the mixture therefore remaining substantially dry. The exact amount of water used depends upon the condition of the mixture, the slate sometimes containing more or less moisture. My invention consists in part in grinding this mixture properly, the object being to much more thoroughly mix the substances by grinding in conjunction with the proper amount of water, so as to cement together with the lime as grains of slate as is possible, thereby making the brick stronger and less liable to be disintegrated by intense heat. The amount of grinding, however, depends upon the quality and nature of the bricks'desired, and the exact amount being more or less immaterial.

The grinding, however, is carried on whilethe mixture is still moist and the lime is slacking, and it is continued until a coherent mass is formed which will not crumble apart when pressed together. A suitable test is to eat a surface area of the take a mass in the hands and pack it together and then press the thumb into the mass. If the mass then merely breaks apart in one or two places, but does not crumble to pieces, the grinding process has reached the final stage. If the mass crumbles the grinding is not sufiioient, or if it is so co erent or plastic as not to break apart at all, the amount of moisture is too great, or the grinding is too much.

The ground material is then passed into the brick-press. Any ordinary brick-press may be used. The material is then put un er a pressure in the neighborhood of two and one-half tons per square inch; the amountof pressure depending upon the density of the brick desired. The bricksare then passed in a heating chamber, which usually consists of along tubular casing, and'steam is passed into the casing, and the bricks are heated thereby for about nine hours, the steam beingkept at a pressure of about 125 pounds. At the end of this heating the bricks are completed.

If the process is properly carried out firebricks are obtained which will stand a continuous tcmperature of 2,285 degrees Fahrenheit. The bricks can be used for building walls, foundations, and the like; or wherever they will be exposed to intense temperature;

and tiles and other articles for mosaic work or the like may be made in a similar manner. The surfaces of the articles may be enameled or colored in any ordinary manner.

I claim as my invention:

1. A process of manufacturing bricks and the like consisting in mixin with burned and granulated coal-mine s ite a proportionately small amount of unslacked lime, in adding an amount of water sufficient to substantially slack the lime vused, in grinding the mixture together until it forms a coherent mass, in pressing the ground mixture into proper shape under a pressure of from two to two and one-half tons per square inch, and in heating the pressed articles for about nine hours in a bath of steam under a pressure of about one hundred and twentg-five pounds.

2. process of manufacturin bricks consisting 1n adding to burned an granulated coal-mine slate from three to five per cent of'unslacked lime with sufiicient water to substantially slack the lime, in grinding the mixture until it forms a coherent mass, in pressing the bricks under a pressure of about two and a half tons per square inch, and in heating the bricks for substantially nine hours at a temperature of about three hundred and fifty'degrees Fahrenheit.

3. An article of manufacture composed of a mixture'of burned and granulated coalmine slate and a roportionately small amount of unslacked lime, with suflicient moisture to substantially slack the lime, the mixture being suitably ground together and pressed into shape, and heated for substantially nine hours at a temperature of about three hundred and fifty degrees Fahrenheit.

In testimony whereof, I hereunto set my hand.

EMIL P. ENGELBRE-CHT. 

